> For the complete documentation index, see [llms.txt](https://www.computersciencea.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.computersciencea.com/unit-1-using-objects-and-methods/1.7-application-program-interface-api-and-libraries.md).

# 1.7 Application Program Interface (API) and Libraries

**Suggested Skills:** 4.A

**LO 1.7.A** — Identify the attributes and behaviors of a class found in the libraries contained in an API.

* **1.7.A.1** — **Libraries** are collections of classes. An **application programming interface (API)** specification informs the programmer how to use those classes. Documentation found in API specifications and libraries is essential to understanding the attributes and behaviors of a class defined by the API. A class defines a specific reference type. Classes in the APIs and libraries are grouped into packages. Existing classes and class libraries can be utilized to create objects.
* **1.7.A.2** — **Attributes** refer to the data related to the class and are stored in variables. **Behaviors** refer to what instances of the class can do (or what can be done with them) and are defined by methods.


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